U.S. patent application number 10/475482 was filed with the patent office on 2004-10-21 for denitrification of aquarium water.
Invention is credited to Ritter, Gunter.
Application Number | 20040206696 10/475482 |
Document ID | / |
Family ID | 7682775 |
Filed Date | 2004-10-21 |
United States Patent
Application |
20040206696 |
Kind Code |
A1 |
Ritter, Gunter |
October 21, 2004 |
Denitrification of aquarium water
Abstract
The invention relates to agents for the removal or reduction of
inorganic nitrogen compounds, especially nitrate, from biological
aquarium waters, containing a biologically degradable polymer,
preferably polycaprolactone (PCL) and to the utilization of said
agents.
Inventors: |
Ritter, Gunter; (Bunde,
DE) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Family ID: |
7682775 |
Appl. No.: |
10/475482 |
Filed: |
May 7, 2004 |
PCT Filed: |
April 24, 2002 |
PCT NO: |
PCT/EP02/04478 |
Current U.S.
Class: |
210/600 ;
528/310 |
Current CPC
Class: |
C02F 3/306 20130101;
C02F 2101/38 20130101; C02F 2103/00 20130101; C02F 2103/20
20130101; A01K 63/04 20130101 |
Class at
Publication: |
210/600 ;
528/310 |
International
Class: |
C08G 069/08; B01D
001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 26, 2001 |
DE |
10120421.3 |
Claims
1. Use of polycaprolactone for the aerobic removal or reduction of
inorganic nitrogen compounds from or in biological container
waters.
2. Use according to claim 1, wherein the inorganic nitrogen
compound is a nitrate.
3. Use according to claim 1, wherein the polycaprolactone is worked
into the bottom while maintaining aerobic conditions.
4. Use according to claim 3, wherein the polycaprolactone is worked
in as granulated material.
5. Use according to claim 3, wherein the polycaprolactone is worked
in in a quantity of 20 g to 200 g per 100 liters container
water.
6. Use according to claim 4, wherein the polycaprolactone is worked
in in a quantity of 60 g to 120 g per 100 liter container
water.
7. Use according to claim 3, wherein the bottom layer consists of
gravel having a particle size of 1 to 8 mm.
8. Use according to claim 7, wherein the bottom layer consists of
gravel having a particle size of 3 to 5 mm.
9. Use according to claim 1, wherein the polycaprolactone is added
to the container water in powder form or as a suspension of a
powder.
10. Use according to claim 9, wherein the powdery polycaprolactone
is added to the container water in the form of a pasty
preparation.
11. Use according to claim 9, wherein the powdery polycaprolactone
is added to the container water in an amount of 5 to 20 mg/liter
water.
12. Use according to claim 11, wherein the powdery polycaprolactone
is added to the container water in an amount of 10 mg/liter
water.
13. Use according to claim 1, wherein the polycaprolactone is
worked into coated large surfaces to produce the removal or
reduction in aerobic working conditions.
14. Use of polycaprolactone to produce agents for the aerobic
removal or reduction of inorganic nitrogen compounds, in particular
nitrate, from biological container waters.
15. Use according to claim 14, wherein the inorganic nitrogen
compound is a nitrate.
16. Filtering agent for container water filters containing
polycaprolactone under aerobic conditions.
17. Filtering agent according to claim 16, consisting of a
homogeneous mixture of filtering agent and polycaprolactone.
18. Filtering agent according to claim 17, wherein the
polycaprolactone is added to the filtering material in an amount of
25 to 75% by volume.
19. Filtering agent according to claim 18, wherein the
polycaprolactone is added to the filtering material in an amount of
50% by volume.
20. Filtering agent according to claim 16, wherein the filtering
material is gravel having a particle size of 2 to 5 mm.
21. Filtering agent according to claim 16, wherein 20 to 250 g
polycaprolactone, preferably 60 to 120 g, are contained therein per
100 l container water.
22. Fleece filter bag containing a filtering agent according to
claim 16.
23. Use of polycaprolactone to produce filtering agents according
to claim 1.
Description
[0001] The invention relates to agents for the removal or reduction
of inorganic nitrogen compounds, in particular nitrate, from
biological container waters containing a biologically degradable
polymer, preferably polycaprolactone (PCL) and to the use of these
agents.
[0002] The daily feeding of fish and other water organisms causes a
regular introduction of organic nitrogen compounds in aquarium
systems.
[0003] In the primarily aerobically operating filtering systems,
the introduced or eliminated organic nitrogen compounds are
degraded to form nitrate by the intermediary steps ammonia/ammonium
and nitrite whose concentration remains low.
[0004] Since the denitrification activity is considerably lower in
most cases than the nitrification activity in the aquarium systems,
this results in a continuous increase in the nitrate
concentration.
[0005] Although the nitrate anion is only very slightly toxic for
fish, endeavours are nevertheless made to slow down the increase in
nitrate or to keep the nitrate concentration low.
[0006] In addition to ion exchange processes for reducing the
nitrate which, however, produce secondary undesirable effects, the
process of denitrification is used. The denitrification is
associated with largely anaerobic conditions and the presence of
degradable carbon compounds.
[0007] Since the formation of nitrate by nitrification occurs
almost continuously, it is expedient to also allow the
denitrification to take place more or less continuously. The amount
of nitrate being added daily in only a low concentration also makes
it possible to omit large substance conversions during
denitrification. Therefore, difficult to dissolve organic,
biologically degradable polymers are very well suited as slowly
reacting C sources.
[0008] To date, the following processes are known which use the
BDPs (biologically degradable polymers):
[0009] a) Granulated material and molded/shaped parts consisting of
polyhydroxybutyrates (PHB) which are placed in the ground on the
bottom of the aquariums to create anaerobic degradation conditions.
PHB is built up by special bacterial species as an energy reserve
substance and embedded in the cells. Therefore, as natural
material, it is easily degradable. Other BDPs were not used in
aquarium systems.
[0010] b) Boley, Muller et al. placed granulated PHB and
polycaprolactone (PCL) in special anaerobic reactors under strict
anaerobic reaction conditions which only have a very small flow
(0.3-0.5 l/h) for the O.sub.2 limiting to degrade nitrate. The
amounts of granulated material used were about 280-380 g per 100 l,
i.e. they were very high.
[0011] In comparison to the prior art, the agents, materials or
processes according to the invention offer considerable advantages
and/or also surprising functional and mechanical improvements for a
person skilled in the field.
[0012] In comparison to the described prior art, the use of
granulated material consisting of polycaprolactone (PCL) offers the
following serious advantages:
[0013] Considerably better industrial availability, since there is
no mass producer for PHB at this time.
[0014] Substantial cost advantages, since PHB is about 2 to 3.5
times more expensive than PCL.
[0015] In addition, it was surprisingly found that PCL as a
synthetic-chemically produced material is similarly easily
degradable as PHB.
[0016] PCL exhibits a surprisingly different degradation behaviour
compared to PHB when nitrate is removed in that it already results
in a completely sufficient nitrate reduction under non-anaerobic or
even under aerobic conditions for aquarium conditions.
[0017] When using PCL granulated material, it was surprisingly
shown that it was just under aerobic operating conditions that a
quicker, more effective nitrate reduction is obtained than under
anaerobic conditions. This fact is surprising and could not be
expected with conventional BDPs according to the prior art.
[0018] Although it is already known according to the prior art to
mix granulated material and molded bodies consisting of PHB with
the bottom layer of aquariums for a reduction in nitrates, the use
of PCL granulated material in the bottom layer of aquarium systems
was not carried out to date.
[0019] From known or compiled results from experiments with PHB
granulated material, a reaction behaviour similar for PCL (as BDP)
was expected, namely
[0020] a) the degradation of nitrate by denitrification under
preferably anaerobic conditions in the bottom,
[0021] b) an increase, promotion of the denitrification with the
creation of largely anaerobic conditions.
[0022] However, surprisingly, it was found that PCL in the bottom
degrades nitrate all the more effectively the more coarse-grained
the bottom layer is made.
[0023] In a comparative test, 70 g PCL granulated material (round
to oval balls, diameter of about 4 mm, content >99%
polycaprolactone) per 100 l aquarium water were mixed in aquariums
with 10 to 20 l bottom matter consisting of
[0024] a) sand (<1 mm)
[0025] b) fine gravel (.o slashed. 1-2 mm)
[0026] c) medium coarse gravel (.o slashed. 2-3 mm)
[0027] and the increase in nitrate of the aquarium occupied by fish
and fed daily was measured over a period of 3 months.
[0028] An Aquarium Not Treated with PCL was Used as a
Comparison.
[0029] The following gradation of the test results according to the
prior art was suprising and an opposite trend would have been
expected:
[0030] a) Sand (.o slashed. 1 mm)
[0031] The nitrate content increased in the control aquarium in the
test period from 49 mg/l to 128 mg/l; only a low decrease in
nitrates was found in the aquarium treated with PCL. The nitrate
increased from 49 mg/l to 109 mg/l.
[0032] b) Fine gravel (.o slashed. 1-2 mm)
[0033] The nitrate degradation was considerably more intense.
[0034] The nitrate concentration increased from 49 mg/l at the
start to 74 mg/l, in the control test to 135 mg/l.
[0035] c) Medium coarse gravel (.o slashed. 2-3 mm)
[0036] In this case, the nitrate reduction was even more clearly
pronounced:
[0037] From 49 mg/l at the start, a decrease in nitrate to only 40
mg/l could even be seen; in the control test, an increase to 136
mg/l.
[0038] A further experiment with gravel having a particle size of
3-5 mm resulted in a nitrate increase of 18 mg/l at the start to 33
mg/l after 3 months, while the control exhibited the following
nitrate concentrations: 18 mg/l to 104 mg/l. The resultant nitrate
concentration was still under the value for medium coarse gravel
(.o slashed. 2-3 mm).
[0039] In contrast to the control aquariums not treated in which
the nitrate content increased further, the nitrate content remained
constant in the PCL-treated aquariums after about 2-3 months, at a
level dependent on the PCL dosage.
[0040] If PCL granulated material of about 4 mm in diameter are
mixed in fine (.o slashed. 1-2 mm), even better in medium coarse
(.o slashed. 2-3 mm) or even coarse gravel (.o slashed. 3-5 mm),
the following nitrate concentrations set in in the treated
aquariums, dependent on the bottom layer mixture, with various PCL
dosages in the period of 3 months:
[0041] 1) Various types of bottom mixtures, PCL dosage: 70 g/100 l
water:
[0042] a) sand (.o slashed.<1 mm)--increase from 49 to 109 mg/l
NO.sub.3
[0043] b) fine gravel (.o slashed. 1-2 mm) increase from 49 to 74
mg/l NO.sub.3
[0044] c) medium coarse gravel (.o slashed. 2-3 mm)--constant until
decline in the range 47 over 27 to 40 mg/l NO.sub.3
[0045] d) coarse gravel (.o slashed. 3-5 mm)--increase from 18 to
33 mg/l NO.sub.3.sup.-
[0046] 2. Coarse gravel (.o slashed. 3-5 mm) with various PCL
dosages after 3 months:
[0047] a) 0 g/100 l PCL: increase from 18 mg/l to 104 mg/l
NO.sub.3.sup.-
[0048] b) 25 g/100 l PCL: increase from 18 mg/l to 86 mg/l
NO.sub.3.sup.-
[0049] c) 50 g/100 l PCL: increase from 18 mg/l to 60 mg/l
NO.sub.3.sup.-
[0050] d) 100 g/100 l PCL: reduction from 18 mg/l to 8 mg/l
NO.sub.3.sup.-
[0051] The process according to the invention for nitrate limiting,
control and reduction by mixing PCL granulated material with fine
to coarse gravel can be carried out very easily by simply mixing
the PCL granulated material in the bottom mixture of the aquarium
system.
[0052] The application only has to be repeated every 6-12 months.
It acts advantageously on the water quality, that anaerobic
conditions in the coarse-grained bottom layer mixture that is
thoroughly flowed through by water are not required and are also
not produced by the process. As a result, anaerobic decomposition
processes and the H.sub.2S release by sulfate reduction can be
avoided.
[0053] The growth of the water plants rooting in the bottom layer
mixture is not negatively affected by this, but even clearly
promoted.
[0054] The following dosages of PCL granulated material (.o
slashed. about 4 mm) have shown to be advantageous for mixing in
fine to coarse gravel, namely 20 g/100 l water to 200 g/100 l
water, preferably 60-120 g/100 l water.
[0055] Since PCL is not dependent on anaerobic reaction conditions,
the use of PCL granulated material in aerobic filtering systems is
also possible.
[0056] According to the aforementioned prior art, PCL granulated
material were used in the mixture with PHB granulated material in
anaerobic reactors operating in the secondary flow with a very
small flow (0.3-0.5 l/h) and high dosage (280-380 g/100 l) for the
anaerobic nitrate degradation.
[0057] It was therefore highly surprising and, according to the
prior art, completely unexpected that PCL granulated material (.o
slashed. about 4 mm) can also be used advantageously under aerobic
conditions, i.e. in filtering chambers or filtering units in the
main stream (with O.sub.2 saturated water) at high flow rates of
20-500 l/h to lower nitrate and even ammonium and nitrite in
aquarium systems.
[0058] However, the use of PCL granulated material as sole
filtering medium in the filter chamber of an inner filter was shown
to be unsuitable, since a considerable decrease of the flow rate
could already be ascertained after about 2 to 4 weeks, so that a
filtering function was no longer given. The cause was the formation
of slime about the granular particles which ultimately resulted in
the formation of an almost water-impermeable, agglutinated filter
filling consisting of slime-coalesced PCL.
[0059] Although nitrate was removed from the aquarium water at the
beginning by the application described above, it was only as long
as the filter still showed a flow, i.e. after about 2 to 4 weeks,
the nitrate removal also ceased for the aforementioned reasons.
[0060] However, if the PCL granulated material are diluted by an
addition of 25-75% by volume of gravel, preferably having a
particle size of 2-5 mm, and mixing it thoroughly, a filter
material is obtained which no longer exhibits the functional
problems appearing with pure PCL granulated material. The filtering
chamber of an inner filter was filled with a 50:50 mixture and the
long-term behavior observed. The filtering effect and the nitrate
degradation remained problem-free over a period of months.
[0061] The described PCL/gravel mixture should also be suitable for
filling other filtering systems as a filtering material, e.g. outer
filter, inner filter with filter chambers, pot filter systems, etc.
Advantages of these filtering mixtures are:
[0062] no agglutination by binding slime
[0063] double filtering effect, namely normal biological filtering
plus nitrate degradation
[0064] simple exchange when the nitrate degradation is
exhausted.
[0065] Instead of gravel, any other commercial filter granulated
material consisting of natural substances such as pumice,
sandstone, basalt, etc. or of synthetic materials can, of course,
also be used as dilutant for PCL granulated material in filtering
chambers.
[0066] The aforementioned problems when using pure PCL granulated
material were also not found when using PCL granulated material in
fleece filter bags. In this case, the filter bags were only
partially filled with about 20-60% of the overall volume and
renewed every 4 weeks. Since it is very easy to exchange such
filter bags and only a small fraction of the PCL granulated
material is degraded in 4 weeks, the PCL dosage is kept almost
constant and thus also the rate of dosage-dependent nitrate
reduction.
[0067] The dosages of the PCL granulated material in the
application of the invention are considerably less than according
to the prior art.
[0068] Even 20-40 g/100 l, 35 g/100 l in the experiment, are
already sufficient to limit the increase in nitrate to 50-60 mg/l.
Higher dosages (up to 100 g/100 l) are still considerably more
efficient.
[0069] In addition to nitrate, ammonium and nitrite are also
effectively removed from the aquarium system in this case.
[0070] When using 100-250 g PCL/100 l, existing ammonium and
nitrite concentrations were reduced to almost 0 mg/l within 0.5 to
1.0 weeks.
[0071] To reduce the nitrate concentration, the following
experiments were performed:
[0072] PCL granulated material were inserted in various dosages in
water-permeable fleece bags in the main filter flow. The water flow
was 30-1000 l/h, preferably 50-500 l/h.
[0073] 35 g, 70 g and 105 g PCL were filled into the fleece bags
per 100 l.
[0074] During the test time of 3 months, the following nitrate
concentrations appeared:
[0075] a) control (0 g/100 l PCL)--increase in nitrate from 26 mg/l
to 175 mg/l,
[0076] b) 35 g/100 l PCL--increase in nitrate from 26 mg/l to 62
mg/l,
[0077] c) 70 g/100 l PCL--decrease in nitrate from 26 mg/l to 20
mg/l,
[0078] d) 105 g/100 l PCL--decrease in nitrate from 26 mg/l to 12
mg/l.
[0079] The documented influence of the nitrate concentrations were
obtained even though nitrate was constantly formed over the
nitrification by feeding the fish occupants (see control as
comparison) and even though the water conditions remained
constantly in the aerobic range.
[0080] The aerobic character of the nitrate reduction method can
also be found in the sulfate reduction not observed in our studies.
The sulfate content changes in the same manner in all test
variations:
[0081] a) control (0 g/100 l PCL)-113 mg/l to 146 mg/l,
[0082] b) 35 g/100 l PCL-115 mg/l to 144 mg/l,
[0083] c) 70 g/100 l PCL-115 mg/l to 142 mg/l,
[0084] d) 105 g/100 l PCL-114 26 mg/l to 143 mg/l.
[0085] A further positive effect of the water treatment with PCL
granulated material was ascertained during the biological
activation of the nitrification.
[0086] Experiments to Decrease the Ammonia and Nitrite
Concentration:
[0087] In the PCL aquariums, the highest intermediate
concentrations of ammonia and nitrite were a slightly to clearly
less than in the untreated control.
[0088] The positive side effect of the reduction in NH.sub.4.sup.+
and NO.sub.2.sup.2- concentrations can be clearly intensified with
higher PCL dosages.
[0089] If higher PCL dosages are used in the fleece bags which were
also used in the nitrate reduction, existing NH.sub.4.sup.+ and
NO.sub.2.sup.- concentrations (e.g. 0.25 mMol/l) can be quickly
reduced to almost 0 and the formation of increased NH.sub.4+ and
NO.sub.2.sup.- concentrations, e.g. during the activation phase
from newly set up aquariums, can be pushed back.
[0090] This is associated with a substantial improvement of the
water quality for water organisms.
[0091] Dependent on the dosage, the following surprisingly good
results can be obtained:
[0092] a) 120 g/100 l PCL: 5.0-6.0 mg/l NH.sub.4.sup.+ and 9.0-10.0
mg/l NO.sub.2.sup.- are completely eliminated within a week,
[0093] b) 240 g/100 l PCL: 5.0 mg/l NH.sub.4.sup.+ are almost
completely eliminated within 0.5 weeks, 12.0 mg/l NO.sub.2.sup.-
within 0.5-1 week.
[0094] The danger to fish feared to date when setting up new
aquariums due to intermediately appearing maximum concentrations of
ammonium and nitrite can be overcome by a suitable treatment with
PCL.
[0095] During the first 4-6 weeks, about 100-250 g/100 l PCL,
preferably 120-180 g/100 l PCL, are inserted into the filter.
[0096] Fish-endangering NH.sub.4.sup.+ and NO.sub.2.sup.-
concentrations are thereby safely avoided. In addition, excessive
nitrate concentrations (e.g. 25-100 mg/l NO.sub.3.sup.-) prevailing
in the initial water are also quickly reduced in this phase.
[0097] After 6 weeks, the natural nitrification has ceased.
NH.sub.4.sup.+ and NO.sub.2.sup.- concentration peaks should then
also no longer be feared with reduced PCL amounts (as used for the
nitrate reduction).
[0098] The PCL dosage can then be reduced to values, e.g. 50-80
g/100 l, which are sufficient for the remaining minimization of the
nitrate level.
[0099] Further Effects of the Treatment of Aquarian Systems with
PCL:
[0100] In addition to the agents, processes and methods according
to the invention described under 3 for a reduction in the
concentration or elimination of nitrate and other inorganic species
(NH.sub.4.sup.+/NH.sub.3 and NO.sub.2.sup.-), further effects were
observed (chemically and biologically) which contribute to promote
the water organisms and stabilize the water chemistry:
[0101] 1. stabilization of the carbonate hardness and thus the pH
value/range,
[0102] 2. release of CO.sub.2 by continuous oxidation of PCL (by 02
and/or nitrate),
[0103] 3. promotion of water plant growth and nitrification,
and
[0104] 4. low to moderate reduction of the phosphate
concentration.
[0105] Areas of Application for the Agents and Processes of the
Invention
[0106] Due to the very good tolerance and the very low toxicity of
PCL, the following areas of application are feasible:
[0107] 1. reparation of aquarian water (freshwater and salt water)
in the home and professional area.
[0108] 2. Preparation of garden pond water.
[0109] 3. Preparation of water in aquaterriums, e.g. to hold water
tortoises.
[0110] 4. Rehabilitating eutrophied natural waters.
[0111] 5. Preparing freshwater and salt walter in large aquariums,
basins, ponds, tanks in public aquariums, zoos, in intensive fish
farming, in shrimp breeding and culture.
[0112] 6. Preparing N/ammonia rich waste waters from the milk,
meat, food industry, brewery, agriculture (animal husbandry),
leather industry and other industrial branches with comparable
waste water problems.
[0113] Generally, excessive inorganic N compounds can be eliminated
from all waters. The purified waters have an increased water
quality and organism as well as waste water and environmental
compatibility.
[0114] Summary of the Agents and Processes According to the
Invention
[0115] Agents According to the Invention
[0116] Advantageously, granulated material of polycaprolactone,
purity >99%, about 4 mm, are used.
[0117] However, all technologically appropriate production
variations can also be used, such as e.g. injection molds which can
be made of PCL, e.g.
[0118] spheres, cylinders, cubes, rectangular parallelipipeds,
inter alia smooth or with any inner and outer surface structure
desired,
[0119] extruded parts, such as e.g. rods, fibers, webs, hollow
tubes and also hollow profiles,
[0120] blow molds, such as hoses, films, etc.
[0121] Processes According to the Invention
[0122] The PCL bodies obtained are used in the water of aquarian
systems and other water systems according to the dosage particulars
defined in the description to reduce the nitrate, ammonia and
nitrite concentration.
[0123] Mixing with Gravel or Bottom in General
[0124] PCL granulated material, molded bodies in the dosage 20
g/100 l to 200 g/100 l water, preferably 60 g/100 l to 120 g/100 l
water, are mixed in the gravel having a particle size of 2-6 mm in
order to lower and stabilize the nitrate content to low or lower
concentrations.
[0125] Use in Filtering Systems
[0126] PCL granulated material, molded bodies are used in the main
stream of filters (flow 30-1000 l/h, preferably 50-500 l/h) in
filter chambers, fleece bags, gauze bags or other water-permeable
containers:
[0127] a) To reduce the nitrate content:
[0128] 20 g/100 l to 200 g/100 l water, preferably 60 g/100 l to
120/100 l water.
[0129] b) To reduce the ammonia, nitrite (and nitrate) content:
[0130] 50 g/100 l to 500 g/100 l water, preferably 100 g/l to 250
g/100 l water.
[0131] The uses of PCL granulated material described above mixed
with the bottom layer and in aerobic filter systems require a
certain maintenance expenditure and comprise a partially
undesirable manipulation with first use or subsequent dosing:
[0132] a) The PCL is gradually degraded by oxidative
microbiological processes over a period of 6-12 months. The
reduction of the nitrate degradation efficiency resulting therefrom
requires a subsequent dosing which is, in part, inconvenient to
handle.
[0133] b) In particular the subsequent dosing into the bottom layer
is not easily accomplished in an established aquarium.
[0134] c) To maintain or correct the nitrate degradation
efficiency, the nitrate content of the water should be measured at
specific intervals, e.g. once a month, to maintain or increase the
desired nitrate reduction by a subsequent dosing in the event that
the nitrate concentration increases again.
[0135] These handling disadvantages may be avoided by the
alternative agents and processes described in the following.
[0136] Use of PCL Powder as Nitrate Reducing Water Additive:
[0137] If one uses the substantially more reactive PCL powder
instead of the PCL granulated material and simply adds the powder
to the container water in periodic dosages, then it is surprisingly
found that this treatment results in a reliable, dosage-dependent
and permanent nitrate reduction.
[0138] In this case, the weekly dosing of PCL powder is fully
sufficient.
[0139] The PCL powder which is added to the container water,
insoluble in water and merely suspended, is partially absorbed by
the filtering system and reaches between the bottom particles
(sand, gravel) in part to there activate the nitrate reduction
under largely aerobic conditions, the results of which are
described in the following.
[0140] Introducing Various Dosages of PCL Powder Into the Container
Water.
[0141] The following amounts of PCL powder are added once a week to
aquariums with current container conditions and average plant and
fish population and easily mixed with the water:
[0142] a) 0 mg/l PCL powder (control)
[0143] b) 5 mg/l PCL powder
[0144] c) 10 mg/l PCL powder
[0145] d) 20 mg/l PCL powder
[0146] The following dosage-dependent nitrate concentrations were
ascertained over a test period of 24 weeks:
[0147] a) (Control) Constant nitrate increase from 23 mg/l to 232
mg/l.
[0148] b) (5 mg/l) Nitrate increase from 22 mg/l to 74-76 mg/l
after 12 weeks, then no further increase in nitrate up to 24
weeks.
[0149] c) (10 mg/l) Nitrate increase from 22 mg/l to 43 mg/l after
24 weeks. An intermediate maximum of 54 mg/l was attained after 6
weeks, followed by a decrease of the nitrate content to 43
mg/l.
[0150] d) (20 mg/l) The nitrate content decreased over a maximum of
38 mg/l after 4 weeks to 6 mg/l after 24 weeks.
[0151] It was concluded from the experiment that a dosage of 10
mg/l PCL powder per liter of water which is appropriate in practice
is sufficient to prevent the nitrate content from increasing to
more than 40-50 mg/l over long periods.
[0152] Significant advantages of the new process according to the
invention are the simple handling (simple dosage of the recommended
amount, once per week) and the maintenance and control-free nitrate
reduction over any long periods.
[0153] By varying the dosage, the desired, sustained stable nitrate
level can be adapted, e.g. also to the population density with
fish.
[0154] Dosage of 10 mg/l PCL Powder in Various Water
Conditions:
[0155] The weekly dosage of 10 mg/l PCL powder deemed appropriate
in practice was subjected to a long-term test under various
container conditions. The carbonate hardness (KH) of the water was
varied.
[0156] The following experiment was performed at KH 2.degree. dH
and KH 11.degree. dH. (Length of experiment--20 weeks)
[0157] Once per week, 10 mg/l PCL powder was added to the
experimental aquariums with current container conditions and
average plant and fish population which differed only in the water
chemistry (KH) and lightly mixed with the container water. The
following nitrate concentrations were measured over the test period
of 20 weeks:
[0158] a) Soft, mineral-lacking water (carbonate hardness: about
2.degree. dH)
[0159] Control (without dosage of PCL powder): continuous nitrate
increase from 2.5 mg/l to 150 mg/l after 20 weeks.
[0160] With the same PCL dosage of 10 mg/l, the tested PCL variants
only differed in the concentration of carbonate hardness additive
which has no affect on the nitrate degradation.
[0161] Variant A (10 mg/l PCL powder): from 2.5 mg/l over a maximum
of 25 mg/l after 6 weeks, the nitrate content fell to 10.5 mg/l
after 20 weeks.
[0162] Variant B (10 mg/l PCL powder): from 2.4 mg/l over a maximum
of 26 mg/l after 8 weeks, the nitrate concentration dropped again
to 14.3 mg/l.
[0163] b) Medium-hard tap water (carbonate hardness: about
11.degree. dH):
[0164] Control (without dosage of PCL powder): The nitrate
concentration increased continuously from 25.5 mg/l to 170 mg/l
after 20 weeks.
[0165] Variant A (10 mg/l PCL powder): from 25.4 mg/l
NO.sub.3.sup.-, the nitrate content increased to a maximum of 30
mg/l after 3 weeks and then dropped continuously to 14.3 mg/l after
20 weeks.
[0166] Variant B (10 mg/l PCL powder): from 25.4 mg/l
NO.sub.3.sup.-, the nitrate content increased to 32 mg/l after 3
weeks and then dropped to 12.4 mg/l after 20 weeks.
[0167] Use According to the Invention, Types of Application:
[0168] The use of PCL powder for nitrate reduction in container
water can take place in various application forms:
[0169] a) Pure PCL powder in dry form. A measuring spoon may be
used for dosing and measuring.
[0170] b) Aqueous suspension of PCL powder in defined composition.
According to the prior art, known suspension stabilizers are added
to the suspension, e.g. a thickening hydrocolloid. Example: Xanthan
in a suitable amount. The amount of suspended PCL powder in the
product is determined from the product dosage, e.g. in a milliliter
of product suspension per 4-liter container water and the desired
dosage of PCL powder.
[0171] A typical example is an aqueous, stabilized suspension
containing 40 g PCL powder per liter. To obtain a weekly dosage of
10 mg/l PCL powder in the container water, 1 ml of the suspension
must be added per 4 l water.
[0172] c) Aqueous suspension of PCL powder in defined composition
to which further functional additives are added. It was shown to be
especially advantageous if PCL powder and a suspension stabilizer
were added to a multifunctional liquid product, as described in WO
01/21533.
[0173] In addition to sodium citrate, citric acid, ferric citrate,
citrate complexes of tracer elements and B vitamins, saccharose, 40
g/l PCL powder were added to the product solution. The addition of
PCL powder significantly improves the nitrate-reducing effect of
the multifunctional product described in WO 01/21533 and as a
result also improves the attainable water quality to a previously
unknown degree and completes the effective spectrum with a very
good nitrate degradation. This improves the product considerably
and makes it possible to omit changing the water in the aquarium
over long periods (also more than 6 months).
[0174] Summary of the Process Based on PCL Powder:
[0175] 1 mg/l to 100 mg/l, preferably 5 mg/l to 20 mg/l of PCL
powder are added to the container water periodically, e.g. daily,
every 2 or 3 days, weekly, every 2 weeks, monthly, preferably
weekly.
[0176] The agent of the invention can be PCL powder itself and/or
comprise all feasible, PCL powder containing preparations which are
functionally and technologically appropriate and feasible, e.g.
[0177] aqueous suspensions,
[0178] suspensions in other functional liquid products, e.g. such
as described in WO 01/21533,
[0179] pasty preparations, etc.
[0180] The preparations may contain any additives desired, e.g.
suspension stabilizers, thickeners, colorants and odorous
substances and also substances according to the prior art.
[0181] As already described for the use of PCL granulated material,
the addition, insertion of PCL in container systems can also
produce the reduction of ammonia and nitrite, in addition to the
reduction of nitrate.
[0182] When using PCL powder, corresponding concentration
reductions of ammonia and nitrite are also observed with comparable
effectiveness.
[0183] In this case, increased dosages of PCL powder, e.g. 10-100
mg/l weekly, preferably 20-80 mg/l weekly, are shown to be
especially advantageous.
[0184] Use of Further PCL Application Forms Having a Large
Surface:
[0185] The use described above for reducing nitrate with the
extremes, PCL granulated material having a relatively small
surface, on the one hand, and PCL powder with an extremely large
surface, on the other hand, makes it clear that all feasible
application forms of PCL, the surface of which is similarly large
as for PCL powder or lies between powder and granulated material,
are also suitable for use in container systems to obtain similar,
comparable effects.
[0186] In addition to the application forms already described in
the first application or technologically appropriate production
variations, PCL may be used in other variants, especially with a
large surface, in container systems to reduce the concentrations of
nitrate and also ammonia and nitrite, e.g.
[0187] as fleece, fiber webs,
[0188] as foam of various pore sizes, e.g. ppi 5 to ppi 50, the PCL
foam being produced according to conventional methods according to
the prior art,
[0189] as PCL coating of materials having a large surface, i.e. as
applied PCL layer on mineral, organic-natural, organic-synthetic
materials,
[0190] as PCL coating of porous materials (organic, inorganic) by
placing thin PCL layers onto and into these materials, as fine foil
leaf,
[0191] as thin PCL coatings on any unnatural, non-living decorative
articles in aquariums, e.g. on stones, roots, figures,
[0192] as thin PCL coatings on plastic plants, filter wadding.
[0193] Thin PCL coatings can, for example, be produced by dipping,
immersing the materials in liquid PCL (FP.apprxeq.60.degree. C.!).
After cooling, the immersed materials harden the PCL film to form a
thin, solid coating.
[0194] The dosage of PCL in the described application forms having
a large surface is 1 g to 200 g per 100 l water, preferably 10 g to
100 g per 100 l water, in the container systems, e.g.
aquariums.
* * * * *